Hi,
Just wanted to say I had the same issue. Win 8.1 64-bit, Origin client, Zero Hour had been working for months without any issues. Then a few days ago when I went to launch it, the dialog box with Generals and Zero Hour would come up, but when I clicked on either, nothing would happen. Generels.exe was running according to Task Manager, but the game wouldn't launch. The PLAY button was greyed out, as were other options. When I went into Task Manager and killed the process (generals.exe), then the PLAY button became active again.
For those interested, it was recorded as an Application Hang Event ID 1002 in Event Viewer :
The program Generals.exe version 1.0.0.1 stopped interacting with Windows and was closed. To see if more information about the problem is available, check the problem history in the Action Center control panel.
Process ID: d8
Start Time: 01d003fc6f889409
Termination Time: 4294967295
I had reinstalled and tried a number of other things, but it acted in the same way. Then I found this post and disabled "Enable Origin in Game" and that worked. Zero Hour once again launches as it always did.
tks.